7,569 research outputs found
Isolation and characterisation of 17 microsatellite loci for the red-billed chough (Pyrrhocorax pyrrhocorax)
Peer reviewedPostprin
Influence of static Jahn-Teller distortion on the magnetic excitation spectrum of PrO2: A synchrotron x-ray and neutron inelastic scattering study
A synchrotron x-ray diffraction study of the crystallographic structure of
PrO2 in the Jahn-Teller distorted phase is reported. The distortion of the
oxygen sublattice, which was previously ambiguous, is shown to be a chiral
structure in which neighbouring oxygen chains have opposite chiralities. A
temperature dependent study of the magnetic excitation spectrum, probed by
neutron inelastic scattering, is also reported. Changes in the energies and
relative intensities of the crystal field transitions provide an insight into
the interplay between the static and dynamic Jahn-Teller effects.Comment: 7 pages, 6 figure
Exchange interactions and temperature dependence of the magnetization in half--metallic Heusler alloys
We study the exchange interactions in half-metallic Heusler alloys using
first-principles calculations in conjunction with the frozen-magnon
approximation. The Curie temperature is estimated within both mean-field (MF)
and random-phase-approximation (RPA) approaches. For the half-Heusler alloys
NiMnSb and CoMnSb the dominant interaction is between the nearest Mn atoms. In
this case the MF and RPA estimations differ strongly. The RPA approach provides
better agreement with experiment. The exchange interactions are more complex in
the case of full-Heusler alloys CoMnSi and CoCrAl where the dominant
effects are the inter-sublattice interactions between the Mn(Cr) and Co atoms
and between Co atoms at different sublattices. For these compounds we find that
both MF and RPA give very close values of the Curie temperature slightly
underestimating experimental quantities. We study the influence of the lattice
compression on the magnetic properties. The temperature dependence of the
magnetization is calculated using the RPA method within both quantum mechanical
and classical approaches.Comment: New figures and discussio
The Weak Clustering of Gas-Rich Galaxies
We examine the clustering properties of HI-selected galaxies through an
analysis of the HI Parkes All-Sky Survey Catalogue (HICAT) two-point
correlation function. Various sub-samples are extracted from this catalogue to
study the overall clustering of HI-rich galaxies and its dependence on
luminosity, HI gas mass and rotational velocity. These samples cover the entire
southern sky Dec < 0 deg, containing up to 4,174 galaxies over the radial
velocity range 300-12,700 km/s. A scale length of r_0 = 3.45 +/- 0.25 Mpc/h and
slope of gamma = 1.47 +/- 0.08 is obtained for the HI-rich galaxy real-space
correlation function, making gas-rich galaxies among the most weakly clustered
objects known. HI-selected galaxies also exhibit weaker clustering than
optically selected galaxies of comparable luminosities. Good agreement is found
between our results and those of synthetic HI-rich galaxy catalogues generated
from the Millennium Run CDM simulation. Bisecting HICAT using different
parameter cuts, clustering is found to depend most strongly on rotational
velocity and luminosity, while the dependency on HI mass is marginal. Splitting
the sample around v_rot = 108 km/s, a scale length of r_0 = 2.86 +/- 0.46 Mpc/h
is found for galaxies with low rotational velocities compared to r_0 = 3.96 +/-
0.33 Mpc/h for the high rotational velocity sample.Comment: Accepted for publication in the Astrophysical Journa
Kinematics and Mass Profile of AWM 7
We have measured 492 redshifts (311 new) in the direction of the poor cluster
AWM~7 and have identified 179 cluster members (73 new). We use two independent
methods to derive a self-consistent mass profile, under the assumptions that
the absorption-line galaxies are virialized and that they trace an underlying
Navarro, Frenk & White (1997) dark matter profile: (1) we fit such an NFW
profile to the radial distribution of galaxy positions and to the velocity
dispersion profile; (2) we apply the virial mass estimator to the cluster. With
these assumptions, the two independent mass estimates agree to \sim 15% within
1.7 h^{-1} Mpc, the radial extent of our data; we find an enclosed mass \sim
(3+-0.5)\times 10^{14} h^{-1} M_\odot. The largest potential source of
systematic error is the inclusion of young emission-line galaxies in the mass
estimate.
We investigate the behavior of the surface term correction to the virial mass
estimator under several assumptions about the velocity anisotropy profile,
still within the context of the NFW model, and remark on the sensitivity of
derived mass profiles to outliers. We find that one must have data out to a
large radius in order to determine the mass robustly, and that the surface term
correction is unreliable at small radii.Comment: LaTeX, 5 tables, 7 figures, appeared as 2000 AJ 119 44; typos and Eq.
9 corrected; results are unaffecte
Recommended from our members
Using data insertion with the NAME model to simulate the 8 May 2010 Eyjafjallajökull volcanic ash cloud
A data insertion method, where a dispersion model is initialized from ash properties derived from a series of satellite observations, is used to model the 8 May 2010 Eyjafjallajökull volcanic ash cloud which extended from Iceland to northern Spain. We also briefly discuss the application of this method to the April 2010 phase of the Eyjafjallajökull eruption and the May 2011 Grímsvötn eruption. An advantage of this method is that very little knowledge about the eruption itself is required because some of the usual eruption source parameters are not used. The method may therefore be useful for remote volcanoes where good satellite observations of the erupted material are available, but little is known about the properties of the actual eruption. It does, however, have a number of limitations related to the quality and availability of the observations. We demonstrate that, using certain configurations, the data insertion method is able to capture the structure of a thin filament of ash extending over northern Spain that is not fully captured by other modeling methods. It also verifies well against the satellite observations according to the quantitative
object-based quality metric, SAL—structure, amplitude, location, and the spatial coverage metric, Figure of
Merit in Space
Potential drivers for schistosomiasis persistence: population genetic analyses from a cluster-randomized urogenital schistosomiasis elimination trial across the Zanzibar islands
The World Health Organization's revised NTD Roadmap and the newly launched Guidelines target elimination of schistosomiasis as a public health problem in all endemic areas by 2030. Key to meeting this goal is elucidating how selective pressures imposed by interventions shape parasite populations. Our aim was to identify any differential impact of a unique cluster-randomized tri-armed elimination intervention (biannual mass drug administration (MDA) applied alone or in association with either mollusciciding (snail control) or behavioural change interventions) across two Zanzibarian islands (Pemba and Unguja) on the population genetic composition of Schistosoma haematobium over space and time. Fifteen microsatellite loci were used to analyse individual miracidia collected from infected individuals across islands and intervention arms at the start (2012 baseline: 1,522 miracidia from 176 children; 303 from 43 adults; age-range 6-75, mean 12.7 years) and at year 5 (2016: 1,486 miracidia from 146 children; 214 from 25 adults; age-range 9-46, mean 12.4 years). Measures of genetic diversity included allelic richness (Ar), Expected (He) and Observed heterozygosity (Ho), inbreeding coefficient (FST), parentage analysis, estimated worm burden, worm fecundity, and genetic sub-structuring. There was little evidence of differential selective pressures on population genetic diversity, inbreeding or estimated worm burdens by treatment arm, with only the MDA+snail control arm within Unguja showing trends towards reduced diversity and altered inbreeding over time. The greatest differences overall, both in terms of parasite fecundity and genetic sub-structuring, were observed between the islands, consistent with Pemba's persistently higher mean infection intensities compared to neighbouring Unguja, and within islands in terms of infection hotspots (across three definitions). These findings highlight the important contribution of population genetic analyses to elucidate extensive genetic diversity and biological drivers, including potential gene-environmental factors, that may override short term selective pressures imposed by differential disease control strategies. Trial Registration: ClinicalTrials.gov ISRCTN48837681
- …